1. Field of the Invention
The present invention relates to an optical deflecting device used in an optical scanner of a light scanning unit and so on.
2. Description of the Related Art
Conventionally, there is known an optical deflecting device in which a polygon mirror, a galvano-mirror, or hologram scan are used as a deflecting mechanism which deflects a light beam outputted from a light source. In the deflecting device, a mirror or hologram is provided on a rotating mechanism, which rotates around one axis, and the light beam is deflected by operating the rotating mechanism. Accordingly, the light beam only scans in one-dimension and does not scan in two-dimension.
In such a deflecting device, in order for the light beam to scan in two-dimensions, extra structures are required. Using a polygon mirror, it is required that the angles of inclination of the mirrors relative to an axis of rotation should be different. In the hologram scan, it is required that a rotating circular plate comprises a plurality of areas on which different holograms are provided. Further, if it is required that the two-dimensional scanning should be controlled more accurately, the deflecting mechanism should comprise both a polygon mirror and a hologram scan. Namely, the structure of the deflecting device becomes large and complicated. Further, a number of scanning lines is limited by a number of mirrored surface or holograms.